Banana puree is used in the bakery, ice cream and baby food industries. In many applications, especially in baby food, a puree free of seeds, i.e., the dark degenerated ovule which occur within the edible flesh of the banana fruit, is especially desirable.
Furthermore, it is also desirable to avoid the product discoloration caused by the natural enzyme, banana polyphenoloxidase, reacting with various diphenolic compounds in the presence of air. Discoloration also is known to result from the reaction between metals such as tin or zinc and "peel rag", a term used to describe the vascular bundles loosely attached to the banana skin but often left on the peeled fruit.
Banana puree has been traditionally produced by pulping fresh ripe banana fruit, removing the air therefrom, and flash sterilizing the pulped fruit, followed by immediate rapid cooling to prevent the aforementioned discoloration and flavor degradation. Such conventional methods involve fine grinding to reduce the size of the seeds and peel rag, an operation that makes such impurities difficult to remove later.
Another method includes the use of a finisher prior to deaeration. However, in order to protect the color, the bananas are acidified with citric acid and antioxidants such as ascorbic acid, or sulfur dioxide is added. In general, acidified bananas do not have a typical fresh banana flavor.
Still further, U.S. Pat. No. 2,507,564 discloses yet another alternative method of avoiding discoloration of ripe bananas by the control heating of banana puree in the presence of added sugar.
None of the traditional procedures are completely successful in eliminating seeds, peel rag and other fibrous material. Furthermore, such procedures employ relatively expensive heat exchange equipment that is slow to accomplish temperature change, with attendant detrimental effect on product color and flavor.